Added consume_query

[That3Percent]

This PR adds a new API consume_query:

/// Parses a single ExecutableDefinition and returns an AST as well as the remainder of the input
pub fn consume_query<'a, S>(s: &'a str) -> Result<(Definition<'a, S>, &'a str), ParseError>
where
    S: Text<'a>,
{ .. }

There are 3 tests showing the functionality.

Resolves #35

I apologize ahead of time that rustfmt went to town on any file that I saved. If you prefer the original formatting or want to make all the formatting changes as a separate commit or something let me know what you need and I can re-make the changes (they aren't that complicated)

[That3Percent]

Anything I can do to help get this merged?

[tailhook]

Sorry, for late reply. This PR is extremely hard to review. Please send your changes without reformatting everything (especially since rustfmt makes code worse here in few places at least).

[tailhook]

I like d2225bd. But we can probably at least set recursion limit on TokenStream object, so it's possible to override.